In the prior art some jaw members for tubular shafted surgical instruments are known. In European Patent Application EP 1 712 187 A2, for example, a jaw member is shown in which the two branches are connected elastic resiliently on a common base. In the region of their distal ends which are intended to hold the surgical clip and to press the surgical clip together and to apply the clip thereby the two branches exhibit on their outer sides a sliding surface, respectively. To close the jaw member and thus to apply the clip, the jaw member is shifted to proximal relative to the shaft in which it is arranged (thus the jaw member is partly drawn towards the handle member into the shaft or the shaft is pushed over the jaw member) and the distal edge of the shaft slides along the sliding surfaces. Through the inclination of the sliding surfaces relative to the axis of the shaft, the distal ends of the branches are urged inward, while the proximal ends of the branches are held by the base.
In this way the branches perform a rotational movement, respectively, around the point at which the branches are connected to the base. An opening operation of the jaw member is done without a guidance and is exclusively guaranteed by the elasticity of the branches that urge in the original position when the jaw member during opening operation is pushed out of the shaft.
A comparable jaw member is also shown in the International Patent Application WO 2008/127 968, even when the instrument shown there overall differs greatly from the instrument described above.
Even more significant is the rotational movement of the branches during opening and closing of the jaw member from the US patent application US 2005/0171560 A1. There the distal regions of both branches are hinged to the base and rotate around the attachment point. Also at this construction the clip is applied by the distal edge of the shaft which is sliding onto the sliding surfaces, which are provided on the outer sides of the branches, and thus pressing the branches inwards.
The problem with this kind of jaw members is that they have always the same closing geometry, more specifically, that at first always the distal ends of the branches touch each other or slide past each other and that the contact or the past sliding of each other of the more proximal regions of branches follows. In clip applicators this means that the clip is always closed from the distal end. For other surgical instruments such as endoscopic scissors for example this design of a jaw member is not useful for this reason.
Another problem with this kind of jaw members is that the opening movement of the jaw member/jaw assembly is realized only by the elasticity of the branches/arms of the jaw member/jaw assembly. The opening movement of the jaw member is done without any guiding. Should a piece of tissue or another part/obstacle end up between the front edge of the shaft and a branch/arm of the jaw member/assembly, could this hinder the opening operation of the jaw member/assembly, then the instrument first has to be removed from the patient's body to remove the tissue/obstacle to be subsequently reintroduced into the patient. This leads to delays and disturbances in the operation flow.